Process for preparing a metallized explosive



Patented June 8, 1965 ice amazes raocnss :r' PREPARENG A. ll/EETALLIZED nxsrosrvn Frank D. Pa rich, Freepert, Tex, assignor to The Dow (Ihemicai Company, Midland, Mich, a corporation of Delaware No Drawing, Filed Apr. 25, 1963, Ser. No, 275,519

3 Claims. (Eli. 149-4) This invention relates to explosives and more particularly is concerned with a novel process for preparing an explosive composition having a substantially uniform distribution of fine metal particles therein.

known in the explosives art. However, because of their density and low bulk volume per unit mass, when such etal particles are employed with an oxidizer or explosive component, particularly with liquid materials or free-fiowing bulk materials, they tend to settle out in the composi- Therefore, to obtain and maintain suspension of such metals throughout the composition, the mix must be continuously agitated and/ or a gelling or thickening agent must be employed.

With explosives employing larger metal particles wherein these are of such a shape, size or configuration to be substantially self-supporting, e.g. form a core with interconnecting cavities, and, may be of such a bulk density so as to achieve co-volume with the oxidizer or explosive component this settling is not a problem. However, many times it is advantageous to provide a mixture of coarse and fine metal particles to facilitate the explosive reactivity of the mix. To illustrate, small met-a1 particles, which ordinarily are readily ignitable, when employed in a mixture With coarser metal particles, can serve as initia tion sites, reaction promoters and a kindle for the larger particles. It is a principal advantage of the present invention to provide a novel process for preparing a metallized explosive wherein finely divided metal particles are substantially uniformly distributed throughout an explosive composition.

it is also an object of the present invention to provide a novel process for assuring that in a metallized explosive composition employing both fine metal particles and coarse metal particles there is no settling of the line metal par-' ticles in the composition without having to employ gelling or thickening agents therein.

It is an additional object of the present invention to provide a process for preparing a metallized explosive wherein metal particles are in closer contact than results from a simple physical mixture of particles and therefore renders these more efiective.

-t is a further object of the present invention to provide a process for rendering more sensitive to detonation explosives metallized with coarse metal particles.

These and other objects and advantages readily will become apparent from the detailed description presented hereinafter.

In carrying out the present novel process, coarse particles of a light metal are contacted with a second light metal in a manner so as to provide a multiplicity of finely divided particles of the said second light metal dispersed over and affixed onto the surface of said first light metal coarse particles. The resulting coarse metal-finely divided metal composite is admixed with an explosive or oxidizer component which gives an explosive composition when mixed with the metal thereby to provide a metallized eX- plosive having a distribution of fine metal particles positioned throughout the final product.

The term light metal as used herein is meant to include magnesium, aluminum, magnesium alloys, aluminum alloys and the like light metals and mixtures thereof. Magnesium alloys refers to those metals having at least about percent aluminum. Aluminum alloys refers to those metals having at least about 70 percent aluminum.

The term coarse metal particles as used herein is meant to include slab face scalpings, machine turnings, Grignard chips, chopped scrap, millings, foils, strands, needles, bars, sponges, tubes and the like, These particles may be one quarter inch or more in diameter and four to six inches or more in length. To illustrate, commercially available magnesium Grignard chips pharmaceutical grade have the following approximate dimensions; about .010" (thickness) x 0.125" (height) x 0.50" (length). In general, these particles are of such a congfiuration so as to be non-equiaxed. Preferably, these coarse particles to provide a self-supporting core or structure having interconnected channels or passages. The oxidizer or explosive component is introduced into the interconnected cavities composition wherein the metal core and oxidizer or explosive component both co extend substantially over the entire volume occupied by the composition.

Finely divided particles means material-s wherein the substantial portion pass a No. 40 U.S. Standard Sieve and wherein the majority of the individual particles are a maximum size of about mesh U.S. Standard Sieve.

The introduction onto ticles to the surface of the by metal spraying techniques, e.g. flame spraying as by a wire-fed metallizing gun, adhesively aliixing one to the other, heating one or the other of the metal forms and pressure joining the heated and cool metal together, etc. The amount of fine particles allixed to the coarse particulate metal can be predetermined over a wide range of conan explosive particle is not enseries of individual To illustrate, magnesium slab-faced scalping cnips (having an average thickness of from about A.; to 1 inch, a width of about /2 inch and a length of about 1 /2 inches) were sprayed with aluminum using a metallizing wire-gun to provide a 50-50 weight percent composite of fine-coarse particulate metal. Measurement would have been retained on a 100 mesh U.S. Standard Sieve, about 31 percent were of a diameter so as to pass a 100 mesh but would be retained on a 200 mesh Standard Sieve, about 21% would have and about 6 percent were minus 325 mesh U.S. Standard Sieve size particles.

it is to be understood that in the present process, coarse and line particles of like metals can be joined. Likewise affixed to readily available magnesium Grignarcl chips. The so-prepared metal particles can be employed with any or" a Wide variety of traditional explosives or oxian dizers which will provide an explosive composition. Particularly suitable explosives and oxidizers include for example, ammonium nitrate, TNT, free flowing dynamites, black powder, and the like.

An effective explosive is obtained when the so-prepared fine-coarse metallized particles are shaped into a self-supporting core and an aqueous, ammoniacal or aqueous-ammoniacal solution of ammonium nitrate substantially saturated with respect to the ammonium nitrate is added thereto to provide substantially coextensive volumes of metal and oxidizer. Divers Solution (ammonium nitrate dissolved in ammonia) or commercially available solutions substantially saturated with ammonium nitrate dissolved in ammonia and having from about 4 to about 7 percent by weight water or more are pre: ferred oxidizer solutions.

The following examples will serve to further illustrate the present invention but are not meant to limit it thereto.

Example 1 A quantity of magnesium slab-faced scalping chips were spray coated with aluminum to provide a'metallized product having about a 50/50 weight ratio of magnesium and aluminum. aluminum particles on the magnesium surfaces indicated an approximate range (effective diameter) equivalent to the following U.S. Standard Sieve analysis: -20+40 mesh-8%, -40+100 mesh-35%, -100+200 mesh-- 31%, -200+325 mesh-21% and 325 mesh-%. The resulting metal produce clearly showed a magnesium matrix with the small aluminum particles randomly affixed to the surface thereof.

About 2 pounds of the metal particles were placed in a 5 inch diameter x 6 inch high container forming a self-supporting core. About 3 pounds of an aqueous ammoniacal ammonium nitrate. solution (approximate composition 69.2 cent ammonia-5.5% water) was poured over the chips and filled the container approximately to the top level of the packed metal chips. 2A Procore (160 gram) explosive initiating booster was centered in the mix, this being attached to a 50 grains per foot Pr-imacord detonating fuse. The Primacord fuse was pulled through the lid of the container and the container then sealed. The free end of the Primacord fuse was armed with a No. 6 electric blasting cap attached by a lead line to an initiator. The load was buried about 38 inches in beach sand and detonated. Good detonation resulted producing a crater having a diameter of about 10.3 feet and a depth of about 3.2 feet.

Example 2 A 5 lb. explosive load prepared in accordance with the teaching of Example 1 was subjected to the standard military rifle bullet sensitivity test as reported in Military Explosives, Department of The Army Technical Manual TM9-l910, Department of the Air Force Technical order TO11A-l-34, p. 49. Complete detonation was achieved.

As a control, unmetallized (i.e. not having fine particles affixed thereto) magnesium slab-faced scalping and aluminum turnings in the same weight proportion were physically blended and utilized with Divers Solution in a substantially identical explosive composition gave no veidence of detonation when subjected to the standard military rifle bullet test.

In a manner similar to the foregoing, magnesium sprayed aluminum chips can be utilized with TNT; fine particles of magnesium alloy can be affixed to magnesium machine turnings and these blended with free flowing dynamite; a mixture of finely divided aluminum and magnesium particles can be affixed to the surface Particle size distribution of the resulting percent ammonium nitrate-25.3 percomposition. This latter of coarse aluminum alloy chips and these employed in with ammonium nitrate oxidizer to prepare an explosive composition.

Various modifications can be made in the present invention without departing from the spirit or scope thereof for it is understood that I limit myself only as defined in the appended claims.

I claim:

1. A novel process for preparing a metallized explosive composition which comprises;

(a) providing a source of coarse nonequiaxed particles of a first light metal,

(b) flame-spraying a multiplicity of finely divided particles of a second light metal onto the surface of said coarse particles thereby to provide a composite finecoarse metal particle, said finely divided particles of said second light metal forming a discontinuous series of individual particles on said coarse nonequiaxed particles of said first light metal and said finely divided particles of said second light metal not entirely covering the surface of said coarse particles of said first light metal, said coarse particles consisting of from about 10 to about Weight percent of said composite and said finely divided particles consisting of from about 90 to about 10 weight percent of said composite, said first light metal and said second light metal being selected from the group consisting of magnesium, aluminum, magnesium alloys and aluminum alloys, and

(c) admixing an explosive 2. A process comprises;

(a) providing a source of coarse nonequiaxed magnesium chips;

(b) flame-spraying aluminum onto the surface of said chips thereby to firmly afiix finely divided aluminum particles onto the surface of said coarse magnesium chips, the flame-sprayed aluminum particles being of a size such that the substitial portion pass a No. 40 US. Standard Sieve, the aluminum-magnesium content of the resulting fine-coarse particulate metal composite being about 50 weight percent aluminum and about 50 weight percent magnesium, said aluminum particles forming a discontinuous series of individual particles on said magnesium chips and said aluminum particles not entirely covering the surface of said magnesium chips, and

(c) admixing about 40 parts by weight of said finecoarse particulated metal composite with about'60 parts by weight of an ammonium nitrate solution,

member therewith. for preparing a metallized explosive which said ammonium nitrate solution being a substantially saturated solution of ammoniumnitrate in a solvent selected from the group'consisting of water, ammonia and mixtures thereof. 3. The process as defined in claim 2 wherein Divers Solution is admixed with said composite fine-coarse particulate light metal.

References Cited by the Examiner UNITED STATES PATENTS 1,268,030 5/18 McCoy 117-119 X 2,816,012 12/57 Walton 149-43 X 2,836,484 '5 58 Streng et a1 149-42 2,899,338 8/59 Goetzel et al. 117-65 2,992,086 7/61 Porter 149-43 X 3,044,911 7 62 Fritzlen 14943 X 3,056,701 10/ 62 Fritzlen 149-42 3,094,443 6/63 Hradel 149-l CARL D. QUARFORTH, Primary Exriminer.

REUBEN EPSTEIN, Examiner. 

1. A NOVEL PROCESS FOR PREPARING A METALLIZED EXPLOSIVE COMPOSITION WHICH COMPRISES: (A) PROVIDING A SOURCE OF COARSE NONEQUIAXED PARTICLES OF A FIRST LIGHT METAL, (B) FLAME-SPRAYING A MULTIPLICITY OF FINELY DIVIDED PARTICLES OF A SECOND LIGHT METAL ONTO THE SURFACE OF SAID COARSE PARTICLES THEREBY TO PROVIDE A COMPOSITE FINECOARSE METAL PARTICLE, SAID FINELY DIVIDED PARTICLES OF SAID SECOND LIGHT METAL FORMING A DISCONTINUOUS SERIES OF INDIVIDUAL PARTICLES ON SAID COARSE NONEQUIAXED PARTICLES OF SAID FIRST LIGHT METAL AND SAID FINELY DIVIDED PARTICLES OF SAID SECOND LIGHT METAL NOT ENTIRELY COVERING THE SURFACE OF SAID COARSE PARTICLES OF SAID FIRST LIGHT METAL, SAID COARSE PARTICLES CONSISTING OF FROM ABOUT 10 TO ABOUT 90 WEIGHT PERCENT OF SAID COMPOSITE AND SAID FINELY DIVIDED PARTICLES CONSISTING OF FROM ABOUT 90 TO ABOUT 10 WEIGHT PERCENT OF SAID COMPOSITE, SAID FIRST LIGHT METAL AND SAID SECOND LIGHT METAL BEING SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM, ALUMINUM, MAGNESIUM ALLOYS AND ALUMINIUM ALLOYS, AND (C) ADMIXING AN EXPLOSIVE MEMBER THEREWITH. 